Offshore Log: Re-inventing the Wheel
Calypso was designed and built to be steered by a tiller. With her double-ended hull form and big outboard rudder, fitting a wheel system was more than a challenge. In fact, it was almost impossible without tearing out the cockpit and starting over.
But our experience during the first year of cruising made us look seriously at wheel steering. With her split backstays, tiller travel was limited to just over 28° either side of center—far less than the 34° considered standard. This made for some hair-raising maneuvering under power.
In addition, our first long sail included a lot of heavy reaching, and the 5-1/2' tiller provided marginal steering leverage in those conditions. For Maryann, hand steering in bad weather was impossible.
We first approached Will Keene of Edson to help us design a wheel system. Edson actually builds a cable and quadrant steering system for double-enders, and if I had planned it in from the beginning, we could have fitted the Edson system. The space needed for the quadrant, however, was occupied by our propane locker.
I refused to resort to hydraulic steering, as the loss of feel was unacceptable.
Instead, we turned to Whitlock, an English company represented in the US by PYI, which also imports the Max-Prop.
The Whitlock system that interested us was the Mamba, a mechanical system incorporating torque tubes and gear boxes rather than cables and quadrant. It is a system often used on big European boats with complex installation problems. The advantage of the Mamba is that because there is no quadrant to swing, the system can be fitted into relatively small spaces. Mechanical advantage is provided by one of several different reduction gear boxes.
After a lot of measuring and calculating, and many hours spent on the phone with PYI’s Whitlock point man, Phil Quartararo, it appeared the Mamba might fit.
No part of the installation would be easy. Clearance between the bottom of the cockpit sole and the top of the fuel tank is less than 3-1/2", barely enough to contain the Mamba’s drive shafts and universal joints. In addition, the small space behind the cockpit would nearly be a press fit for the bevel boxes, reduction gear box, and autopilot motor.
A heavy support frame would have to be built in the tiny space to bear the enormous loads (both Edson and Whitlock calculated them at over 1,100 ft. lb.) that the huge rudder could impose on the steering system components and the boat.
On the plus side, the system would give as leverage almost four times that of the tiller, and the constraints on rudder travel would be eliminated. Against the maximum calculated tiller loads of 200 lb. at surfing speeds with the rudder hard over, we would see maximum wheel rim loads of about 45 lb. with the 32" wheel.
In addition, Whitlock’s own autopilot motors interface directly with the Mamba bevel box, eliminating gears, chains or additional tiller arms.
We decided to give it a try.
Because time was at a premium and installing the system would require a lot of custom metal and glass fabrication, we hauled Calypso at New England Boatworks (NEB) in Portsmouth, Rhode Island.
NEB has more experience in metalwork and mechanical installations than almost any yard in New England. Steve Cassella, a friend for almost two decades and one of the yard’s owners, agreed to oversee the project, and assigned Dave Bourque as chief problem solver.
Dave and I spent hours snugging up bolts that could only be turned by fingers a fraction of a turn at a time, and which we had to tension using custom wrenches.
The hardest part of the job was creating a watertight seal where the drive arm exits the hull to connect to the rudder. Finally, almost accidentally, we found a drysuit replacement neck seal that was astonishingly close to the right dimensions.
Thanks to soft-spoken but effective persuasion from Ridge White of R.E. White Instruments in Boston, Ritchie Navigation rushed through the construction of a custom 6" Globemaster binnacle compass for us. The Globemaster is, according to White (whose grandfather invented the spherical compass) the best compass in the world.
We would like to have had a gentle shakedown for our new steering system. Instead, we took off for Bermuda.
Hans Bernwall of Scanmar had counseled us to keep our tiller and let the Monitor do the work, since it is easier to set up a good wind vane system with a tiller than a wheel. We got around that one by fabricating a short custom aluminum tiller, which fits into the permanently rigged emergency tiller socket. This allows the Monitor to be coupled directly to the rudder, avoiding the additional friction and complex leads that would have been required in a system driving the rudder through the steering wheel.
The system works great. New England Boatworks is probably the best yard I have ever dealt with. They work hard, charge fair prices, and they do the job right.
Contacts- PYI, Box 536, Edmonds, WA 98020; 800/523-7558, fax: 206/670-8918. New England Boatworks, 1 Lagoon Dr., Portsmouth, RI 02871; 401/683-6110. Ritchie, 234 Oak Street, Pembroke, MA 02359; 617/826-5131, fax: 617/826-7336. Robert E. White Instruments, 34 Commercial Wharf, Boston, MA 02110; 800/992-3045, fax: 617/742-4684.